Usually happens if i go to the Over-world from another dimension. Last time I saw it was on CubeCraft Games, Minerware, Large rectangles of shadows that look dark and lighting smoothness is non-existent. When you go into it, your skin and, if you're holding one, your map in you're off-hand darkens and player arrows darken the further into the shadow you go.
Unfortunately I wasn't able to get a screenshot.
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Thank you for your report!
We're actually already tracking this issue at MCPE-69037, so I will resolve and link this ticket as a duplicate.
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